Abstract: A double-faced Vivaldi antenna is designed and tested.Through optimizing structure design, the feeding efficiency and the impedance bandwidth of the antenna are improved.Meanwhile, the mutual coupling between the elements is greatly reduced when the antenna is used for an array.The measured results show the return loss of the presented antenna is less than -10 dB from 2 to 8 GHz and the average gain is larger than 5 dBi.An ultra-wideband array is also formed by the Vivaldi antenna.In this array, the idea of "staggered arrangement" is adopted.This method can effectively solve the contradiction between the sizes and the spacing of antenna elements.So, the grating lobe of the array is suppressed, and the beam scanning angle range is markedly increased.The simulation analysis shows that the scanning angle of the staggered array of E-field is improved at least 20 degrees in 4-6 GHz.